It has been a long-standing goal in the field of air filtration systems to remove harmful contaminants and particulates, such as bacteria, viruses and molds, from air within an enclosed area, as well as from the surfaces located within the enclosed area, thus maintaining a safe workplace for individuals.
People spend about 75 to about 90 percent of their time indoors where they are exposed to a growing number of health-threatening indoor pollutants. These pollutants can be categorized into three groups: biological contaminants, such as bacteria, viruses, and molds; toxic gases and fumes given off by furniture, carpeting, etc.; and particulates, such as dust and smoke. Approximately half of the major office buildings have contaminated heating, ventilation, and air conditioning (HVAC) systems. If not properly maintained, the HVAC systems are a hotbed for the growth of molds and bacteria, regardless of the age of the building. Occupants of these buildings can be expected to suffer from symptoms related to exposure to these health-threatening indoor pollutants. The problem of health-threatening indoor pollutants is exacerbated when the building is a health facility where not only are there a greater number of harmful health-threatening pollutants present, but occupants of the health facility may be more susceptible to maladies caused by these health-threatening pollutants.
A known solution for removing harmful contaminants from ambient air is the use of air purifiers. Air purifiers use a scientifically advanced process that combines the power of germicidal ultraviolet (UV) light, purifying hydroxyl, activated oxygen, and photo-ionization for purifying air and sanitizing an area. However, existing air purifiers do not use the multiple approach of pre-ionization of the incoming air, high efficiency particulate (HEPA) filtration, and sterilization by use of ultraviolet nm lamps for a more complete solution. Further, most existing air purifiers use small ultraviolet lamps that do not allow adequate time required for sterilization.
Another approach for removing harmful contaminants from surfaces is the use of chlorine to clean water and surfaces. However, chlorine may leave harmful residuals within the drinking water and chlorine also cannot be readily generated on site. The chlorine must be shipped to the site from manufacturers located a distance away from the point of need. During emergency situations, proper handling of chlorine containers may be impractical.
Ozone has been used in municipal drinking water systems to purify and kill microorganisms and bacteria. Ozone, however, is a powerful oxidant and its exposure to humans generally needs to be limited. The U.S. Occupational Safety and Health Administration limits ozone exposure in the workplace to less than 0.1 ppm over an 8 hour period. When used to purify fluids, however, reduction to acceptable levels is generally not a concern because ozone has a half-life of about 8 to about 30 minutes in water (depending on temperature). Therefore, any ozone used to purify municipal drinking water will have decayed to acceptable levels long before it is exposed to human consumption. Use of ozone to sterilize an enclosed air space presents other challenges because the half-life of ozone in air can be as high as about 36 to about 72 hours (depending on temperature). Therefore, if ozone is used to sterilize an enclosed area, depending on the concentration used to sterilize that area, the space may not be suitable for human contact for over a day and a half.
Attempts have been made to sterilize rooms using ozone generation, such as hospital size rooms and larger (i.e., about 1000 ft3 or larger), but such previous attempts have either used large, fixed systems or have not been able to generate sufficient concentrations of ozone to kill any detectable levels of contaminates. Large, fixed systems only sterilize the room to which they are fixed and provide no sterilization to rooms that are not associated with the ozone. Therefore, fixed systems require multiple, expensive systems and increased capital and operating costs. Prior systems have also been ineffective at providing sufficient levels of detectable biocide activity using airborne ozone in hospital sized rooms.
Notwithstanding these and other proposals, a need remains for a sterilization system, especially a mobile system, that effectively provides the user with an ability to sterilize an ambient environment, such as a patient room or mobile operating room in a turnkey manner. In particular, a need remains for a mobile system for filtering out particulates, safely destroying biological contaminants such as by ozone generation, effectively converting the ozone to highly ionized ambient air, and providing for the convenient, efficient removal of the ozone from the environment about the mobile system.